in all reality guys don't care what colour you paint your nails, this is entirely a girl thing...we couldn't care less whether your nails are bright red or dark blue, or uncolored...I can't say we notice girls nails much
Although I don't consider the colour of my nails important (I don't do anything to them besides keep them clean and in good condition), if you want to paint them, go shopping with friends and ask them to test colours you like against your skin. As sad as it sounds, my Mum is much more stylish and pays more attention to these kinds of things, and she always asks me for my opinion on whether the colours she likes suit her skin complexion, and from the ones I think suit her tone, she choses ones she likes the most from that limited selection.
Personally, you could paint your nails any colour and pull it off if you're confident, if you fret a lot, it comes across to others in a more obvious way. You could also consider whether to colours match your favorite outfits in terms of colours contrasting, harmonizing with each other, etc.